Cutter



Aug. 14, 1945. v

L. A. SMITH CUTTER Filed Aug. 11:19:43

Patented Aug. 14, 1945 CUTTER.

Lawson A. Smitlnllos Angeles, Calif., assignor to Robert H. Clark, LosAngeles, Calif. v

Application August 11, 1943, Serial No. 498,213

3 Claims.

This invention has to do with a cutter and has particular reference tofeatures of construction applicable to cutters used for boring or facingand more particularly it relates to cutters of the type in which thereis a central or main body carrying a plurality of separate cutters. Itis a general object of the present invention to provide an improvedconstruction and arrangement of parts in a tool of the charactermentioned.

In cutting tools, and particularly in tools used in machine operations,it is essential that the cutting parts be accurately and firmlysupported, as otherwise it is diflicult, if not impossible, to obtainaccurate results or the cutting action is not smooth or finished. It isdesirable from many standpoints to provide a cutting tool having acentral or main body carrying detachable or replaceable cutters. Suchtools, however, present certain limitations or difficulties, one of themain difficulties being that of gaining sufilcient rigidity. For manyoperations it is essential that the cutters or cutting parts be securelyand rigidly held in the desired positions and with a sectionalconstruction or a build-up device difiiculty has been experienced ingaining this end.

It is also highly important in tools of the char acter and type referredto that the construction employed be simple and inexpensive ofmanufacture and that the cutters be mounted in a manner so that they canbe readily and accurately adjusted.

A cutter of the general type to which I refer is the subject of mycopending application entitled "Cutting tool filed May '7, 1943, SerialNo. 485,984. In that application I show a cutting tool wherein there isa polygonalbody having angularly disposed channels in its sidesto-carrycutters whichare secured in the channelsby suitable clampingdevices applied to the body. This construction is, in general, desirableas it is simple of manufacture and use, is sllfficiently rigid for manypurposes, and it has been found to be commercially practical. It is anobject of my present invention to provide improvements in a cutter ofthe type which is the subject of my said copending application.

By the present invention I have provided a structural arrangement andcombination of parts which makes the assembly more rigid and consequently more suitable for certain classes of work, particularly forheavy work or those types of work which require extreme. accuracy andrigidity.

It is a further object of my invention to provide a cutter of thegeneral type which is the subject of my said copending applicationwherein the several cutting parts or cutters are supported by means ofthe main body so that the main load or thrust borne by the cutter istransmitted or communicated tothe body as close as possible to theactual cutting edge. By my present invention each cutter is supported inachannel formed in the body and the arrangement is such that the forcesor loads borne bythe cutter are communicated directly to the bottom ofthe cuttercarrying channel where the cutter leaves the channel toproject to the work. In other arrangements, such as the arrangementshown in my said copending application, the cutters and body are relatedso that the forces or strains'incidental to operation are mainlycommunicated to the body through the retaining means, there being atendency for the cutter to lift from the channel where it leaves thechannel to project to the work. In other words, with the oldconstruction the cutter is subject to spring from the point where itengages the work to the point where it is held by the retaining means,whereas in my: improved'constru'ction the bottom of the cutter-'carrying channel supports the cutter against spring'or give at'the pointwhere the cutter leaves the'body to project to the work.

The various objects and features of my invention will be fullyunderstood from the following detailed description of a typicalpreferred form and application of my invention, throughout whichdescription reference is made to the accompanying drawings, in which:

Fig. 1 is a side elevation of atypical cutting tool embodying thepresent invention and Fig. 2

is an end elevation of the tool, being a View taken substantially asindicated byline 2-2 on Fig.' 1. My present invention may be embodied invarious forms or types of cutters but is most practical and advantageousin the general type of cutter which is the subject of the said copendingappli cation. In that type of cutter there isa main or central body I0having a supporting shank l l a plurality of angularly disposedcutter-carrying} 3 trated in the drawing.

made sufficiently long to properly accommodate the cutters and theretaining means as, will be hereinafter described. v

The shank ll serves as the means for mounting the body ID in a machineor operating device and is'preferably formed integral with the body. Forordinary machine shop use the shank Il may be tapered in a manner suchas is illus- The cutter carrying channels 12mm providedaround the bodyIt).

words, carried by the body l so that they pro- J'ect dovmwardly andoutwardly from the bottom end of the body and rearwardly with referenceto the direction of rotation of the cutter, the cutting heads or cuttingends of the cutters are dressed to present proper cutting parts. Thecutting end of each cutter is dressed to have a flank portion 25 whichrecedes from what may be termed the leading, substantially vertical edge26. Tlie flankfis curved to be concentric with the principalaxis of thetool when the cutter shaped and proportioned 'aocordingto the particular cutters being used. I

In common practice the cutters are substantially square in cross-sectionand consequently the channels I2? are imade substantially square ,toaccurately I receive the r cutterss The channels arezangularlydisposed:at the sides: of therbody,v

it being: preferred in practice-.to pi-tch them-lat? an angleofwabout 38from. a. plane normal: to,- thelongitudinal axis-of the body; Further,in.

1 practice'it is desirable to locate thecu-ttermarry ing: channels so.that they. open atzthe bottom of: the bodyin! the manner illustratedint-the: drawing. It. isrto-be understood,.of course,.that' j the,cutter carry-ing' channels- 12: are alll pitched equally and formed inlike manner so. that, the. severalouttersare heldv'by' the body'toproject downwardly, andoutwardly fromthe body, at cor resnendingnangles; i

The cutters. I2 are individual: cutting tools formed of stock preferablysquare or substantially square in cross section. 'I:he-01-1ter end:portion-ct each cutter l3'is-dressed1or finished; to present; acuttinghead which I. will hereinafter refer. to in detail: 7 The retainingmeans [4 provided for retains plates 21 which engage over-'thecutters.There 1 is one cap-screw and-one clamp platefo-r: each-- 1 ingthe,-cutters in the channels preferably-in cludes' cap-screws 1 2IJ- threadedinto the sidesof thebodyv-which are channeled to: hold: clampcutter, thecap screw being threaded; intothe body adjacentthechannel and the :clampplate beingin the" nature'of-a-washer or collar-"canried ou the cap:screw to overhang: the cutter;

knurled or roughened so-they; effectively grip; the cutters. I

In accordance I with my present invention the cutter -carrying channels.areangularly: disposed inithe sides of the body Ill so thatthe'cutters"v are pitched to project in adirection outward:

and downward from the-lower'end of: the body 1 and also toproiectrrearwardly with reference 'to The; clamp' faces Zl of the plateare preferably:

the direction of rotation of'the cutter: Referring:

to Fig. 2 of the-drawing-the direction of rota tionof the cutter isindicated by" the arrow-X;

Itwillbe noted that ifthecutter' is viewed:frorn the bottom and isconsidered: rotating in: thedirectinnindicated-by the arrowthe'cuttersnrniecting. fromthe bottom" of the body; instead"of-projectin forwardly -fromthe body with'gref erence to the direction'of rotation; proiect'rearwardlv therefrom. In other-words. theends of'l by the tool.

tool.

, isswithdrawn or set in a retracted position somewhat inward of thesmallest'opening toibe cut When thus formed the shank 25 has side.clearance behindhthe edge 26 when the tool is operatedp=The verticalleading edge 26 may be finished to beparallel with the principal axisof:' theztoolzs'o" that" it operates to finish or ream the boremade bythe tool, or it may, as illustrated; be pitched upwardly and inwardly togive it: a; slight-side cle'aranceil Theifront -or leading; face MY-is;dressed sothat the? cutter has-t a--' suitable back slope l to give the?cuttings clearance; This-slope, together 'withtth'e b'ottonr face -28;defines vthe 'keenness ofzthe cutter? bottom faceaZBQisipreferablyxdressed to' extend rearwardlyand; slightly: upward? fromthepoint1 where: it-intersects the: forward' face 21 'so'zthat there isbottom? clearance: nThe lineof j cinder; of the 'forward," face Z'I: andthet bottorni facea28 forms or: definesi-a bottom cutting; edge It is tobe.- understood' thatz'the particular shape; or) manner ofdressing theicutting partsrof the cutterswill depend I upon the =Work-rto' be: done:by the tool; i

In accordance with my invention when theicut ter-ris .bodily projectedrearwardlywith reference tolthe direction -.of rotation of the-toolritisineces= sarytodress awaytthe'forward porti'onof th'e'zcutr. ting-endof the cutten as-indicated -at Anin:0r.'der.-1to' obtain .the properangleon theeleading face '23? since it: isdesirablethat the cutting:face 2l1rb such as .to recedesomewhat; as= clearly showm in; Fig. 2,from :a-line radial from 'the ,centerof-the;

Inlaccordance withthe principlertaught in my said-0Opending application-it-n-is preferred; inprac-.-- tice to, dress the several cutters:sothat thereds some variationjn them, .forinstance, one of the; cuttersis dressed so that the facet! :is atanlangle.- different than thecorrespondin face of the other cutters, in order to eliminatechatter. sr

The pilot [5, asLhave stated mayabe\adrill; or it maybe asingle pin-suchas I have shown in) the: drawing, It is to beunderstood, of course;that'so'far as thepresent invention is concerned the devicemay-beprovided with a pilQt orhit may. Ice-without apilot ascircumstances require, H

With the arrangement and construction that I'='have described thestrains or forces incidental to' the cutting operation are" communicated.rrom the cutters'to the body in the most advantageous mannerand so asto eliminate tendency for spring or give to occur in the structure.Referring to' Fig: 2% will be'apparent'thatas the cutter is retated inthe direction indicated by the arrow'X andith'e tool is fed intothe-Work, forceis'set up in'. each cutter in the direction'indic'ated bythe arrow B; tending: to force the outer: end 1 of we "cutter-back;Thisforce' is'mainly taken up ci resistedbythe-supporting action ofrtheouterrend portion ofthe cutter-carrying channel bya' a re sistance:occurring substantially? as indicated by the arrow C. The tendency forthe upperor ini' nermost endportion of thelcutter toiliftioutroffitschannel is resisted by the retaining means substantially as indicated bythe arrow D. It will be apparent from the forces thus diagrammed thatthe principal load or strain of work is communicated by the cutterdirectly to the bottom of the channel where the channel opens out at thelower end of the body, and in this way the cutter is supported in themost advantageous manner and there is little or no tendency for theparts to work or spring.

Having described only a typical preferred form and application of myinvention, I do not wish to be limited or restricted to the specificdetails herein set forth, but wish to reserve to myself any variationsor modifications that may appear to those skilled in the art or fallwithin the scope of the following claims:

Having described my invention, I claim:

1. In a rotary cutting tool of the character described, a central bodyhaving a shank at one end and angularly disposed cutter carryingchannels in its sides pitched to extend toward its other end andrearward of the direction of rotation of the tool, elongate cutters withinner and outer sides and each having a cutting edge at its outer endfaced to cut substantially laterally of its length in the direction inwhich the outer side faces, the cutters being carried in the channelsWith their inner sides bearing on the bottoms of the channels and theirouter end portions projecting beyond said other end of the body andrearwardly of the direction of rotation of the tool whereby as the bodyrotates forces set up by working of the cutting edges tend to seat thecutters in the channels, and means retaining the cutters in thechannels.

2. In a rotary cutting tool of the character described, a central bodyhaving a shank at one end and having cutter channels disposedtangentially in its sides and inclined relative to the longitudinal axisof the tool so the lower end portion of each channel extends toward theother end of the body and rearwardly of the direction of rotation of thetool, an elongate cutter in each channel projecting beyond the lower endof the channel and having a cutting part at its lower end facin in thedirection of rotation of the tool to cut as the tool rotates so pressurecaused by cutting tends to seat the cutter in the channel, and meansretaining the cutters in the channels.

3. In a rotary cutting tool of the character described, a central bodyhaving a shank at one end and an angularly disposed cutter carryingchannel in its side pitched to extend toward its other end and rearwardof the direction of rotation of the tool, an elongate cutter with innerand outer sides and having a cutting edge at its outer end faced to cutsubstantially laterally of its length in the direction in which theouter side faces, the cutter being carri d in the channel with its innerside bearing on the bottom of the channel and its outer end portionprojecting beyond said other end of the body and rearwardly of thedirection of rotation of the tool whereby as the body rotates forces setup by working of the cutting edge tends to seat the cutter in thechannel, and means retaining the cutter in' the channel.

LAWSON A. SMITH.

